Amplifying circuit



July 6, 1937.. g, ac sm 2,086,256

AMPLIFYING CIRCUIT Filed Feb; 12, 1952 A Patented July 6, 1937 UNITEDSTATES PATENT, OFFICE AMPLIFYING omourr Harry G. Cisin, Brooklyn, N. Y.Application February 12,- 1932, Serial No. 592,586

13 Claims.

This invention relates to sound amplification and has special referenceto an amplifier for deaf persons.

One important object of the invention is toimprove the generalconstruction of devices of Q to provide a novel form of amplifyingcircuit in which exactly the same circuit is used with alternatingcurrent as with direct current, there being no switches necessary tochange from one circuit to another as is common in devices intended foruse with both alternating and direct current.

With the above and other objects in view, as will be hereinafterapparent, the invention consists of certain novel arrangements of partsand combinations of details hereinafter fully described,

illustrated in the accompanying drawing and specifically claimed.

'In the accompanying drawing the figureshows a wiring diagram of thecircuit of this invention. In this drawing there is shown a pair ofterminals 10 so that, by means of the usual extension cord (not shown),the device may be connected to thesocket of an ordinary house lightingcircuit.

in the circuit there is provided a rectifying tube H and an amplifyingtube I2. The tube ii is provided with a filament l3, a grid M, a platel5 and a cathode l6. The tube I2 is likewise provided with a filamentli, a grid I8, a plate |9 and a cathode 20. One of the terminals lilisconnected by a wire 2| with one element of a switch 22 used simply forthe purpose of turning on and off the current when the device isconnected to the house circuit. A wire' 23 leads from this switch toseries resistances 24 which are, in turn, connected to one end of thefilament l3 by a wire 25. The other end of the filament I3 is connectedto one end of the filament I! by a wire 26 and the remaining end of thefilament I1 is connected to the remaining terminal I0 by a wire 21. Itis of course understood that the resistances 24 are sufficient toprevent burning out of the filaments I3 and I! when the switch 22 isclosed. One of these resistances may be a variable resistance ifdesired.

choke coil 3| is connected by a wire 35 with the terminal 33 and theterminal 34 is connected by a wire 36 with the plate H. The grid I8 isconnected by a wire 31 with the movable element of a variable resistance38 and 'one end of the resistance 38 is connected by a wire 33 with thewire 21. The cathode 20 is connected by a wire 40 with one end of aresistance 4| which has its other end connected by a wire 42 to the wire33. A microphonic receiver 43 has one terminal connected by a wire 44with one end of the primary winding-46 of a transformer. The other endof this primary winding is connected by a wire 46 with the wire 39. Theremaining terminal of the transmitter 43 is connected by a wire 41 withone end of a resistance. 48 which has its other end connected by a wire49 with the wire 2?. The secondary winding 50 of the transformer-has oneend connected by a wire 5| with one end'of the resistance 43 and itsother end connected by a wire 52 to the remaining end of this resistanceby connection of the wire 52 to the wire 39.. A condenser 53 is bridgedacross the wires 39 and 40, being thus in parallel with the resistance4|. Similarly a condenser 54 is bridged across the-wires 21 and 41,being'thus in parallel with the resistance 48. A condenser 65 is bridgedacross the wires 2'! and and a condenser 56 is ID are connected by acommon extension cord with a socket of an ordinary 110 volt circuit. If

'In the operation of the device the terminals the current is alternatingit is immaterial how the connection is made but if direct current isused it is necessary to so make this connection that the wire 2| will beconnected to the positive side of the house or other circuit used as asupply. It may therefore be necessary, if the device does not at firstwork, to turn one of the plugs around in-the usual manner to ensure thewire 2| being positive. The switch being closed, the filaments will becaused to glow and a plate cir cuit will be established through the headset 32 and transformer secondary 50 and this "circuit will, of course,be affected in the usual manner by the action of sound waves on thetransmitter 43. Obviously the intensity of action of the receiver headset may becontrolled by adjustment of the variable resistances and. thusthe volume of sound received by the person wearing the head set may beadjusted in accordance with the extent of his deafness and the loudnessof the voice or other sound desired to be transmitted.

It is intended that the entire apparatus shall be arranged in a compactmanner in a suitable carrying case but it is not deemed necessary hereinto illustrate or describe such a case since it is obvious that the casemay be of any form, material or size which may be found convenient orsuitable.

Furthermore, while the invention is primarily designed to assist personswith impaired hearing it will be plain that it may be put to other uses.For instance, the transmitter may be hidden in a room and connected bylong leads to the remainder of the apparatus worn by a, person inanother room so that the device lends itself to use by a detective.Again the invention may be used as an inter-ofiice or similarcommunicating device.

Among the advantages of this apparatus may be mentioned that iteliminates all trace of hum when used on a direct current circuit andi'. eliminates all objectionable hum when used with alternating current.The invention permits the use of the M filament 13'l-type A. C.--D. C.humless vacuum tube and permits the operation of the filaments atone-half the rated voltage, thus increasing the useful life of tretubeby at least 100%.

There has thus been provided a simple and efiicient device of the kinddescribed and for the purpose specified.

It is obvious that changes may be made in the form and construction ofthe invention without departing from the material principles thereof. Itis not therefore desired to confine the invention to the exact formherein shown and described, but it is desired to include all forms whichproperly come within the scope claimed.

What is claimed, is:

1. In a device of the kind described, a plurality of vacuum tubes eachhaving a plate, a grid, a cathode and a heater filament, a power supplyline leading 'to' the first of said tubes and having the plate and gridof the first tube connected thereto in multiple, a conductive connectionbetween the cathode of the first tube and the plate of the second tubeand including in series therewith a choke coil, a second power line, apair of condensers bridged from the last mentioned-connection to thesecond power line and connected to said last mentioned connection onopposite sides of the choke coil, a conductive connection including avariable resistance and leading from the grid of the second tube to thesecond power line, a conductive connection between the cathode of thesecond tube and the second power line and including a condenser and aresistance in parallel, and a series circuit including the heaterfilaments and an adjustable resistance connected across the power line.

2. In a device of the kind described, a plurality of vacuum tubes eachhaving a plate, a grid, a cathode and a heater filament, a power supplyline leading to the first of said tubes and having the plate and grid ofthe first tube connected thereto in multiple, a conductive connectionbetween the cathode of the first tube and the plate of second tube andincluding in series therewith a choke coil, a second power line, a pairof condensers bridged from the last mentioned connection to the secondpower line and connected to said last mentioned connection on oppositesides of the choke coil, a conductive connection including a variableresistance and leading from the grid of the second tube to the secondpower line, a conductive connection between the cathallel, and aconductive connection between said power lines and having said filamentsconnected therein in series, said last conductive connection including avariable resistance interposed between the first power line and thefilament 01' the first tube. i

3. In an amplifying circuit operable from an alternating current anddirect current source, a first and second terminal connectible to saidsource; a rectifier tube consisting of anode means, cathode means andheater means, said anode means being connected to said first terminal; afilter having an input and output comprising inductance means andcondensersextending trom said inductance means and connected to saidsecond terminal, the inductance lead of said input being connected tosaid cathode; an amplifier tube comprising an individual envelopeenclosing an anode, a cathode and a heater therefor; a translatingdevice, one terminal of said translating device being connected to saidamplifier anode and another terminal of said translating device beingconnected to the inductance lead or said filter output.

4. In an amplifying circuit operable from an alternating current anddirect current source, a first and second terminal connectible to saidsource; a rectifier tube consisting of anode means, cathode means and aheater, said anode means being connected to said first terminal; afilter having an input and output comprising inductance means andcondensers extending from said inductance means and. connected to saidsecond terminal, the inductance lead of said input being connected tosaid cathode; an amplifier tube comprising an individual envelopeenclosing an anode, a cathode and a heater therefor; a translatingdevice, one terminal of said translating device being connected to saidamplifier anode and another terminal of said translating device beingconnected to the inductance lead of said filter output; and aresistance, said resistance and said heaters being connected in seriesbetween said first and second terminals.

5. In an amplifying circuit operable from an alternating current anddirect current source, a

first and second terminal connectible to said source; a rectifier tubeconsisting of anode means, cathode means and a heater, said anode meansbeing connected to said first terminal; a filter having an input andoutput comprising inductance means and connected to said secondterminal, the inductance lead of said input being connected to saidcathode; an amplifier tube comprising an individual envelope enclosingan anode, a cathode and a heater therefor; a translating device, oneterminal of said translating device being connected to said amplifieranode and another terminal of said translating device being connected tothe inductance lead of said filter output; and a resistance, saidresistance and said heaters being connected in series between said firstand second terminals, one terminal of said resistance being connected tosaid first terminal for establishing a voltage drop between said heatersand said first terminal.

6. In a power supply circuit operable .from an alternating currentsource and direct current source for supplying operating current to athermionic amplifier section: means for supplying current to the anodecircuit of said amplifier section comprising a thermionic rectifierincluding an anode and a. heater element, the input of said rectifierbeing conductively connectible to said source, and a filter connectedbetween the output of said rectifier and said anode circuit forsmoothing pulsations oi the rectifier output current; and circuitconnections for supplying current to said heater element from saidsource including a resistance individual to the heater circuit forpredetermining the current flow from said source through said heaterelement.

7. In a power supply circuit operable from an alternating current anddirect current source for supplying operating current to .a thermionicamplifier section having an anode and a heater element: means forsupplying current to the anode circuit of said amplifier sectioncomprising a thermionic rectifier including an anode, a

heatable cathode and a heater element, the anode of said rectifier beingconnectible to a terminal of said source'and a filter connected betweenthe cathode of said rectifier and said anode circuit for smoothingpulsations of the rectifier output current; and circuit connections forconnecting said heater elements in series and to said source including aresistance individual to the heater circuit for predetermining thecurrent flow from said source through said heaters.

8. In a power supply circuit operable from an alternating current anddirect current source for supplying operating current to a thermionicamplifier section having an anode and a heater element: means forsupplying current to the anode circuit of said amplifier sectioncomprising a thermionic rectifier including an anode, a cathode and aheater element, theanode of said rectifier being connectible to aterminal of said source and a filter connected between the cathode ofsaid rectifier and said anode circuit for smoothing pulsations of therectifierv output current; and circuit connections for connecting theheater elements to said source including a resistance individual to theheater circuit, one terminal of said resistance being directly connectedto said rectifier anode and the other terminal of said resistance beingdirectly connected to said rectifier heater element, for establishing avoltage drop between said rectifier heater and said rectifier anodeduring current fiow.

9. In an amplifying circuit operable from an alternating current anddirect current source: a thermionic amplifier section having an anodecircuit; means for supplying current to said anode circuit comprising athermionic rectifier including an anode and a heater element, the anodeof said rectifier being conductively connectible to said source, and afilter connected between the output of said rectifier and said anodecircuit for smoothing pulsations of the rectifier output current; andcircuit connections for connecting-said heater element in series'withsaid source including a resistance individual to the heater circuit andconnected between said rectifier heater andsaid rectifier anode forproducing a difierence in potential betweenvsaidrectifier anode andheater element during current flow.

10. In an amplifying circuit operable from an alternating current anddirect current source: a thermionic amplifier section having an anodecircuit and a heater element therefor; means for supplying current tosaid'anode circuit comprising a thermionic rectifier including an anodeand a heatable cathode. the anode of said rectifier being directlyconnectible to a terminal of said source, and a filter connected betweenthe cathode 01' said rectifier and said anode circuit for smoothingpulsations oi the rectifier output current; and circuit connections forconnecting said heater elements in series and in conductive relationwith said source including a resistance element individual to the heatercircuit for predetermining the current flow from said source throughsaid heaters.

11. In an amplifying circuit operable from an alternating current anddirect current source: a thermionic amplifier section having an anode, aheatable cathode and a heatable element therefor; means for supplyingcurrent to the anode circuit of said amplifier section comprising athermionic rectifier having an individual envelope enclosing an anode, aheatable cathode and a heater element therefor, the input of saidrectifier being conductively connectible to said source, and a filterconnected between the output ct. said rectifier and said anode circuitfor smoothing pulsations of the'rectifier output current: and circuitconnections for connecting said heater elements in series and inconductive relation with said source including a resistance elementindividual to the heater circuit forpredetermining the current flow fromsaid source through said heaters, said heaters having suitableresistance values to normally heat up their associated cathodeelectrodes with substantially said predetermined current fiow.

12. In an amplifying circuit operable from an alternating current anddirect current source: a thermionic amplifier section having an anodecircuit: means for supplying current to the anode circuit of saidamplifier section comprising a thermionic rectifierincluding an anodeand a heater element, the input of said rectifier being conductivelyconnectible to said source, and a filter connected between the output ofsaid rectifier and said anode circuit for smoothing pulsations of therectifier output current; and circuit connections for connecting saidheater elements in series and in conductive relation with said sourceincluding .a. resistance element for predetermining the current fiowfrom said'source. through said heaters, one terminal of said resistanceelement being directly connected tosaid rectifier anode and the otherterminal of said resistance element being directly connected to saidrectifier heater for establishing a substantial difierence in potentialbetween said rectifier anode and rectifier heater during current fiowconditions.

13. In an amplifying circuit operable from an alternating current anddirect current source: a thermionic amplifier section having an anode, aheatable cathode and a heater element therefor; means for supplyingcurrent to the anode circuit of said amplifier section comprising athermionic rectifier tube having an individual envelope enclosing ananode, a heatable cathode and a heater element therefor, the anode ofsaid rectifier being directly connectible toa terminal ,of saidsource.,and a filter connected between the-cathode of said rectifier andsaid anode circuit for smoothing pulsations oi the rectifier outputcurrent; and circuit connections for connecting said heater element inseries and in conductive relation with said source including aresistance element individual to the heater circuit for predeterminingthe current fiow from said source through said heaters, one terminal ofsaid resistance element being directly connected to said rectifier anodeforestablishing a substantial difference in potential between saidrectifier .anode and said heaters during current flow conditions.

- IIfiRRY G. CISIN.

